Voice-current telephone-repeater



G. H. KUHL. VOHIE CURRENT TELEPHONE REPEATER.

APPLICATION FILED MAY 31, 1919.

1 98,728. Patented Nov. 29, 1921.

- 'z'zunfur m Hg UNITED STATES PATENT OFFICE.

GEORGE E. KUHL, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OI ILLINOIS.

VOICE-CURRENT TELEPHONE-REPEATER.

T0 aZZ whom it may concern:

Be it known that I, Gnonon H. KUHL, a citizen. of the United States of America, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Voice-Current Telephone-Repeaters, of which the following is a specification.

My invention relates to an improvement in voice current telephone repeaters and more specifically to an improved method of reversing or switching an amplifier or amplifiers in a long trunk line from one repeating relation to another or to so switch the circuits that voice currents may be repeated from either end of a trunk line to the other.

My invention is in the nature of an improvement on certain prior inventions in which the same result was accomplished, but which required more apparatus to accomplish the same.

Among the objects of my invention are to provide single magnet or relay which is responsive to voice currents to operate a microphone to repeat the currents into another circuit in amplified form, and which also acts as a sensitive relay to control the switching of the amplifiers to repeat in dif-.

:ierent directions over the trunk or to render the amplifier, which repeats in one directioin inoperative, while the other amplifier is repeating in the other direction. Thus it will be seen that my invention relates to combined voice current amplifying repeater and sensitive relay.

In Figure l I have shown a section of a trunk line inductively connected by means of a voice current repeater and controlled in accordance with my invention.

In Fig. 2 I have shown a combined voice current relay and repeater which forms one embodiment of my invention.

1 will now describe the operation of the various circuits and apparatus as controlled while conversation is being relayed back and forth over the trunk line. Assume that a talking circuit including the section shown in Fig. 1 has been established between a calling and a called subscriber and that the subscriber on the west end of the trunk line begins to speak, then voice currents will flow through. the secondary winding 2 and the primary winding 3 of a pair of induction or repeating coils. Current will therefore Specification of Letters Patent. Patented N 29, 1921 Application filed May 31,

1919. Serial No. 300,893.

be induced in the secondary winding 4: to operate the relay repeater 5 in series there with. Relay 5 has an armature or vibrating element at each end thereof, each constructed of light material as illustrated in Fig 2, so that each will have as little effect as possible upon the other. It will be understood that I do not wish to limit myself to the exact construction shown in Fig. 2 which is simply one form of relay that may be used. The armature 6 of relay 5 is attached to one of the elements of the microphone cell 9 to agitate the resistance element 01"- the microphone to cause a corresponding amplified voice current to be generated in the circuit including the battery and primary winding 10 of the induction coil. The armature 7 of relay 5 also responds to variations of current in relay 5 to open the contact between springs 7 and 8, spring 8 being weighted so that it is thrown off to open said contact when spring 7 vibrates, and the contacts remain separated for a greater proportion of time than they are closed. The opening of springs 7 and 8 opens the upper winding of a slow acting relay 11 which is differential and has its lower winding permanently energized. Relay 11 will therefore energize at the first operation of the relay 5 to short circuit the secondary win-cling 12 of the induction coil to render the transmission of voice currents in the opposite direction over the trunk line impossible. The voice current generated in the primary winding 10 induces a like current in its secondary winding 13, which current flows through the primary winding 14 and out to and through the listening parJy at the east end of the trunk.

Now in case the party on the west end ceases speaking the relay 11 will simply be balanced by the energization of its upper winding and will open the springs let. Now should the party on the east end or": the trunk commence speaking. the operation is reversed, that is, current flowing through winding 13 and primary winding 15 induces a current in winding 12, which flows through the relay 16 which corresponds in all respects to the relay 5. Relay 16 in. operating agitates the microphone cell 17 to generate a corresponding current in primary 18 which is thereby repeated to the party on the west end, now listening through second:

.ary Winding 2, and also opens springs 19 and 20 to cause the operation of relay 21 to close springs 22. Springs 22 short circuit Winding 4; to prevent repeating in the opposite direction and also prevents any leakage of the amplified current back to relay 5 to cause singing.

It Will therefore be seen that my invention provides improved switching devices to change the relation of amplifiers to a trunk line and that these devices are so constructed and related that no part oi the voice current is lost, each amplifier being always in readiness to receive and repeat voice currents immediately and also adapted to render the other amplifier inoperative upon receipt of the first Wave of voice current.

Having fully described and ascertained the features and aspects of my invention, What I consider to be new and desire to have protected by Letters Patent Will be pointed out in the appended claims:

What I claim as my invention is:

1. In a telephone system, a pair of lines joined by a voice current repeater, said repeater comprising a pair of amplifiers one for repeating from each line, each amplifier consisting of a voice current relay having one vibrating member directly controllable thereby for repeating voice currents and a separate vibrating member for rendering the other amplifier inoperative also directly controlled by the relay.

2. In a telephone system, a pair of voice current relays for repeating voice currents back and forth over a line, each relay having two armatures one for directly actuating a microphone cell for repeating, and another direotly controlled by the relay for rendering the other relay inoperative.

Signed by me at Chicago, Cook county, Illinois, this 27th day of May, 1919.

GEORGE H. KUHL, 

